1. Field of the Invention
The present invention relates to a steering system for vehicles.
2. Description of Relevant Art
In the steering system for vehicles, rotation of a steering wheel is transmitted through a steering shaft and a rack and pinion mechanism or the like to steered wheels, turning these. When a vehicle turns while traveling with a higher than predetermined speed with the steered wheels turned in either direction, the front wheels which in most cases are the steered ones have a restoring force acting thereon with a tendency to return them to the neutral position. The restoring force is resulted from wheel alignment of the front wheels and self-aligning torque due to deformation of their tires. When the steered wheels are turned at an angle, if the driver does apply no steering forces to the steering wheel, with or without letting the hold go, they tend to return to the neutral position with the restoring force.
The restoring force however is hardly produced when the vehicle travels with a very low speed or while it is in an almost standing state. It is somewhat troublesome in a vehicle parked in a narrow road or driven into a small garage to return the front wheels to the neutral position. It is more or less difficult to complete parking or garaging at such places with the front wheels restored to the neutral position. It however is desirable to have the front wheels as the steered wheels restored to the neutral position, when departing from such places. In a four-wheel steered vehicle, it is desirable that all the four wheels are restored to the neural position.
The present invention has been achieved to effectively solve such a problem in conventional steering systems for vehicles.